Synthesis and biological evaluation of benzimidazolyl substituted aloe-emodin derivatives

Benzimidazolic derivatives of the natural product aloe-emodin were prepared in good yields via aerobic condensation of the corresponding aldehydes with diamines in the presence of potassium iodide as auxiliary reagent. The required aldehydes were easily obtained by oxidation of aloe-emodin or its dimethyl-protected analogue. In vitro antimicrobial activity and cytotoxicity of the synthesized compounds were assessed. Most of the compounds showed either low to moderate antiprotozoal activity, although it was quite aspecific. 3-(1H-Benzo[d]imidazol-2-yl)-1,8-dihydroxyanthracene-9,10-dione showed the highest specificity against Leishmania infantum with IC50 = 4.06 mu M and a selectivity index of 10.29. [GRAPHICS] .